INCIDENCE OF OPTIC NEURITIS IN STOCKHOLM, SWEDEN 1990-1995 - I - AGE,SEX, BIRTH AND ETHNIC-GROUP RELATED PATTERNS

We studied the incidence of monosymptomatic optic neuritis (MON) in St ockholm county, Sweden and its variation with person-related factors. Patients with suspected or diagnosed MON between January 1, 1990 and D ecember 31, 1995 were referred from ophthalmologists and neurologists to a research registry. The diagnosis was based on accepted clinical c riteria only, and verified by an ophthalmologist who examined all the patients. Data were collected by interview using a structured question naire. The crude mean annual incidence, based on 147 patients, 118 fem ales and 29 males, diagnosed with MON, was 1.46 per 100 000 person-yea rs, 2.28 for females and 0.59 for males. The corresponding age-adjuste d incidences were 1.40, 2.28 and 0.53. The age-specific incidence curv e for both sexes suggested a bimodal distribution with peaks at 30-34 years and 45-49 years. The smoothed cumulative incidences in 1 year bi rth cohorts showed a notchy profile, related to bimodality. The incide nce among residents born out of the Nordic countries was low, 0.28 per 100 000. Patients with onset of MON before 40 years of age had a sign ificantly higher frequency of mononuclear pleocytosis in cerebrospinal fluid and shorter duration to conversion to multiple sclerosis. In su mmary, MON occurred in Stockholm at a relatively low frequency, partic ularly among males. The presence of particular birth date and birth pl ace related patterns might be etiologically relevant. (C) 1998 Elsevie r Science BN. All rights reserved.